The use of tertiary amines in the manufacture of polyurethanes is known. A multiplicity of structurally different amines are employed therein as catalysts.
Polyurethanes for the purposes of the present invention are any reaction products between isocyanates, in particular polyisocyanates, and correspondingly isocyanate-reactive molecules. This also comprehends polyisocyanurates, polyureas and also allophanate-, biuret-, uretdione-, uretimine- or carbodiimide-containing isocyanate or polyisocyanate reaction products. The use of tertiary amines in the manufacture of polyisocyanate polyaddition products is preferable.
Polyurethane systems include, for example, polyurethane coatings, polyurethane adhesives, polyurethane sealants, polyurethane elastomers or foamed polyurethane materials, also known as polyurethane foams or PU foams.
Tertiary amines are particularly important in the manufacture of polyurethane foams because a delicate balance has to be achieved here between the “blowing reaction” (water reacts with isocyanate to form carbon dioxide as blowing gas) and the “gelling reaction” (polyols react with isocyanates to form urethanes, which leads to an increase in the molar mass and corresponding gelation) if a high-quality foam is to be obtained.
Polyurethane foams are cellular and/or microcellular polyurethane materials and are roughly subdividable into closed-cell or partly closed-cell rigid polyurethane foams and open-cell or partly open-cell flexible polyurethane foams. Rigid polyurethane foams are overwhelmingly used as insulating materials for example in refrigerator systems or in the thermal insulation of buildings. Flexible polyurethane foams are used in a multiplicity of technical applications in industry and the home, for example for soundproofing, for production of mattresses or for upholstery of furniture. The automotive industry is a particularly important market for various types of PU foams, such as conventional flexible foams based on ether or ester polyol, cold-cure flexible foams, hereinafter also known as cold-cure foams (frequently also as high-resilience (HR) foams), and rigid foams and also foams with properties that are between these classifications. The automotive industry may employ, for example, rigid foams as inner roof liners, ester foams as interior door trim and also for die-cut sun visors, and cold-cure and flexible foams for seating systems and mattresses.
Flexible foams may also be subdivided into cold-cure flexible foams and hot-cure flexible foams, as described for example in EP 2042534 A1, fully incorporated herein by reference.
There continues to be a need for further alternative catalysts, preferably nitrogenous catalysts, in particular alternative amines, suitable for production of polyurethanes and foamed polyurethane materials, preferably suitable for production of low-odour ageing-resistant polyurethane systems having low amine or other emissions, as for example of formaldehyde and/or dimethylformamide (DMF).